There are various methods for manufacturing a liquid jetting head used by an ink jet recording method, which records by jetting recording liquid such as ink. One of the methods is as follows:
U.S. Pat. No. 4,657,631 discloses a liquid jetting head, which will be described next. According to this method, first, the elements for jetting liquid are formed on a substrate. Then, ink passage molds are formed of a photosensitive substance, on the substrate, by patterning. Then, a resin layer is formed on the substrate by coating the substrate with the resin in a manner to cover the ink passage molds. Then, ink jetting holes are formed through the resin layer so that the holes extend from the outward surface of the resin layer to the ink passage molds, one for one. Then, the ink passage molds formed of the photosensitive substance are removed. From the viewpoint of the ease with which the ink passage molds can be removed, a positive resist is used as the photosensitive material for forming the ink passage molds. Further, this method uses photolithographic technologies for forming a semiconductor. Therefore, this method can process, with extreme precision, the photosensitive substances to form the ink passages, ink jetting holes, etc. However, a liquid jetting head manufacturing method which uses a semiconductor manufacturing method has a drawback in that it is only the two directions, parallel to the primary surfaces of the substrate, that the portions of the resin layer, which correspond to the ink passages and ink (liquid) jetting holes, can be controlled in shape when they are formed. That is, this method uses a photosensitive substance as the material for the molds for the ink passages and ink (liquid) jetting holes, and therefore, cannot form the photosensitive layer in multiple sub-layers. That is, it cannot form ink passage molds in such a manner that they are not uniform in the cross section perpendicular to their height direction (direction perpendicular to primary surfaces of substrate). Thus, it is possible that the employment of this method will limit the latitude in the designing of the liquid passage or the like.
U.S. Pat. No. 6,158,843 discloses a method for processing a structural component having liquid passages with the use of an eximer laser. This method controls the depth to which resin film is processed, by changing a part, or parts, of a laser mask in the degree of nontransparency. Thus, this method can three dimensionally control the shape in which the ink passages are formed; it can control the shape in terms of the directions parallel to the primary surfaces of the substrate, and the direction perpendicular to the primary surfaces. However, this method also has a problem. That is, an eximer laser, that is, a laser which this method uses for processing a resin film, is different from a laser used for exposing a substrate for a semiconductor, in that it is higher in brightness in a wide range than the latter. Thus, it is extremely difficult to prevent an eximer laser from fluctuating in its illuminance at the surface to be exposed by the laser; it is extremely difficult to stabilize an eximer laser in its illuminance at the surface to be exposed by the laser. In particular, in the case of an ink jet head for forming a high quality image, the nonuniformity of its ink jetting nozzles in terms of ink jetting characteristics, which is attributable to the nonuniformity in nozzle shape, can be recognized as blemishes in an image. Therefore, it is extremely important to improve the liquid jetting head manufacturing methods and devices in terms of the level of precision at which they can process the materials for a liquid jetting head. Further, there are cases where microscopic patterns cannot be formed because of the taper of the surfaces(s) of the ink jetting nozzles, which results from the processing by a laser.